Photographic emulsion



Patented on. 31, .1939

2.177635 PHOTOGRAPHIQ EMULSION Burt H. Carroll, Rochester, N. Y., and Edward P. Davey, Harrow, England, aasignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application Mayra, 1931, Serial No. 145,534

19 Claims. (o3; 95 -1) This invention relates to sensitized photographic emulsions and more particularly to photographic emulsions, such as those of th gelt lno-silver-halide type, containing one or ore se tizing materials together with one or flnore man-rials which'in themselves do not materially sensitize-photographic emulsions, but which, when mixed or combined with the sensitizing material, act to increase the sensitization produced by the sensitizing material alone. The sensitization produced by our combinations is always greater, in some spectral region, than the sensitization produced bythe sensitizing material alone.- The sensitizing materials of our j' combinations are substance'sgenerally referred to as dyes and more particularly as dyes or the cyanine class.

It is known in the art of making photographic emulsions that certain dyes of the cyanine class '0 alter the sensitivity oi photographic emulsions of the gelatino-silver-haiide kind, when incorporated therein. It is also well known that the sensitization produced by a given dye varies with thetype of emulsion in which it is incorporated.

35 Furthermore, the sensitization of a given emulsion by a given dye may be altered by varying conditions in the emulsion, for example, the sensitization may be increased by increasing the silver ion concentration or by decreasing the so hydrogen ion concentration (1. e.increasing the alkalinity) or both. Sensitization can be increased, for example, by bathing. a sensitized emulsion with water or with solutions of ammonia. This process of altering the sensitization 3g of a sensitized emulsion by-increasing the silver ion.concentration and/or by decreasing the hydrogen ion concentration is commonly called 4:; certain groups of dyes.-- Certain supersensitlzing combinations oi dyes are described in United States Patent; 2,075,046; 2,075,047 and 2,075,048. We have now found a new means of altering the sensitization produced in emulsions by dyes. .0 Since the conditions in the emulsion, e. g. the

hydrogen ion concentration or the silver ion con-1 centration, undergo little or no change in our scribed-in the above patents, because instead of employing combinations of sensitizing dyes, we

employ a mixture or a combination of one or sensitizing substances are chemically combined.

The non-sensitizing substances can be referred to as the supersensitizing substances. In preparing our new supersensitized emulsions, we employ one or more simple cyanine or carbocyanine dyes, while as supersensitizing substances we employ one or more organic amino compounds, such, for example, as one or more amino heterocyclic nitrogen bases.

All object of our invention, therefore, is to,

provide supersensitized photographic emulsions. A further object is to provide a method or altering the sensitivity of sensitized emulsions. A further object is to provide a process for increasing the sensitivity of sensitized emulsions. A still further .object is to provide a photographic element comprising super-sensitized emulsions. Other more specific objects will become apparent hereinafter. v 7

The sensitizing cyanine dyes employed in our inventiomin themselves, sensitize gelatino-silver halide emulsions to maximum sensitivity between about 400 mu. and about 720 mu. The sensitizing simple cyanine dyes employed in our invention contain at leastone pyridine or at least one quinoline nucleus, such as is the case in 2, 2'-

- new method, we shall designate our new method I as a kind of supersensitization. However, our

' us new method is nottobe confused with that decyaninedyes, 5, 6-benzo-2, 2-cyanine dyes,

2, 4"-cyanine dyes, 4, 4'-cyanine dyes, 2, 2'- pyrldocyanine dyes, 4, 4'-pyridocyanine dyes, thia-2'-cyanine dyes, benzothia-2'-cyanine dyes, selena-2'-cyanine dyes, thiazolc-zscyanine dyes, thia-P-cyauine' dyes, selena-4'-cyanine dyes,

thiasolo+4'-cyanine dyes, selenazolo ii -cyanine dyes, r ,benaothia-4'-cyanine dyes and this-2'- UNITED STATES PATENT. OFFICE j Ill pyrldocy'anine dyes for example. The aboverecited simplezcyanine dyesuall of which contain at least one pyridine or at least one quinoline nucleus, belong to the following four classes of dyes, to wit: 2' -eyanine or pseudocyanine dyes,

y-cyanine orisocyanine dyes, 2'-pyridocyanine dyes and 4'-pyridocyanine dyes. The sensitizing contain two heterocyclic nuclei linked through their alpha pomtions by'the trimethenyl chain. The heterocyclic nuclei in the carbocyanine dyes employed in our invention are of the groupquinoline nuclei, such as unsubstituted quinoline,. -methylquinoline or 5, B-benaoquinoline nuclei for example, thiazoles, such as 4-phenylthiaaole, i-methylthiamle, 4, 5-diphenylthiaaole, unsub stituted. thiazole, benzothiasole, u-naphthothiazole or p-naphthothiazole nuclei for example.

' oxazole nuclei, such as benzoxazole, a-naphthoxor joined together by a single methenyl group..

Simple cyanine dyes can be, represented by the followinggeneral formulas:

wherein D represents a divalent organic group, such as a vinylene or a phenylene group, L represents a methylene group, R and R represent organic groups, particularly alkyl groups, x represents an acid radical and Y and Z each represent the non-metallic atoms necessary to complete a heterocyclic nucleus.

- By the term carbowanlne dye", we mean a cyanine dye in which the two heterocyclic nuclei are linked or joined together by a trimethenyl chain. Carbocyanine dyes, of the kind wh the two heterocyclic nuclei are linked by a trlmethenyl chain through their alpha positions,

can be represented by the following general wherein L, R, R, X, Y and Z have the values set forth. under formulas I, II and m above; Carbocyanine dyes representedby-for'mula IV can be called a, a -carbocyanine dyes.

By the term "organic amino compoimds, we mean an organic compound containing an amino group which can be unsubstitutedcr substituted as for example by alkyl groupsor acyl groups.

Cyclic organic amino compounds particularly of the aromatic series are especially useful. Heterocyciic nitrogen bases containing an amino group are particularly advantageously employed in practicing our invention.

Among the simple cyanine dyes which can be employed. in practicing our invention are vthe following: V 4

The benzo-2,2'-cyanine dyes which can be represented by the following, general formula t.

M v e 8,177,885 dyes employed in our invention The 2,2'-dyanine dyes which can be represented by the following formula:

The thia- 2'-cyanine dyes which can be sented by the following formula: 16

' I a VB/ x' The selena-2'-cyanine dyes which can be represented by the following formula:

The thia-2'-pyridocyanine dyes which be 7 represented by the following general formula:-

' p 3 i The bensothia-2'-cyanine dyes which can be represented by the following general formula:

The thiaaolo-T-cranine dyes which can be represented by the following general formula:

v n'x, v,

--The thia-i' cyanine dyes which can be reprev sented by the following general formula:

The thiazolo-4'-cyanine dyes which can be rep resented by the following general formula:

The 4,4'-cyanine dyes which can be represented by the following general formula:

The 4,4'-pyridocyanine dyes which can be represented by the following general formula:

The 2,4'-cyanine dyes which can be represented by-the following general formula:

The 2,2-pyridocyanine dyes which can be prepared represented by the followingformula:

' 5 a a Q 1 2' I 6 2 =CH- 16' t R In the above formulas of simple cyanine dyes, A and B represent hydrogen, alkyl or aryl groups, R and R" represent alkyl groups and X represents an acid radical. In practicing our invention, we have found it advantageous to employ the dye-halides, particularly the dye-iodides (where X represents iodine).

group of two carbon'atoms are particularlyuseful in practicing our-invention. The simple cyanine dyes can be substituted in their nuclei with simple substituents which do not interfere with sensitizing properties, such, for example, as chlorc, bromo, alkyl, alkoxy, amino or the like. As shown in the above formulas, dyes having a fused-on nucleus, for example a benzene ring as-in the case 01 benzothia-2'-cyanine dyes, can be employed.

The aboveiormulas of representative types of 'simple cyanine dyes are not intended to limitour invention, as there are still other well known simple cyanine dyes not depicted above. However, the foregoing will serve to instruct those skilled in the art as to which of the simple cyanine dyes can advantageously be employed in practicingour invention.

The methods of preparing the different simple cyanine dyes are well known and described in .various patents and printed publications.

However, the iollowing will aid those skilled in the art 'in quickly locating the available information.

2,2'-cyanine dyes can be prepared as described by Hamer in J. Chem. Soc., page 206 et seq. (1928). 2,2'-pyridocyanlne dyes can be prepared as described by Brooker and Keyes in Jour. Am. Chem. Soc., vol. 57, page 2488 et seq. (1935). Thia-2'-cyanine dyes and 5,6-benzo-2,2-cyanine dyes can be prepared as described by Hamer in J. Chem. Soc., page 206 et seq. (1928) Selena- 2'-cyanine dyes can be prepared as described by Brooker and Keyes in Jour. Am. Chem. Soc., vol. 57, page 2488 et seq. (1935). 7-alkyl-thia-2' and 4'-cyanine dyes can. be prepared as described in U. S.' Patent 2,060,023. Benzothia'-2-cyanine dyes can be prepared as described by Hamer in J. Chem.'Soc., page 2598 et seq. (1929-). Thiazolo-2'-cyanine and selelazolo-2'-cyanine dyes can be prepared as described in U. S. Patent 1,969,446 (see also British Patent 408,570 and 1 scribed by Braunholtz and Mills in J. Chem. Soc.,

vol. 121, page 2004 et seq. (1922).

'Ihiazolo-4-cyanine dyes can be prepared as illustrated below.

3.3 g. (1 mol.) of 1-methyl-4-phenylthiazole ethiodide and 5.7 g. (2 mol.) of quinoline ethiodide were dispersed in 25 cc. of absolute ethyl alcohol containing 1.3 g. ofv 85% potassium hydroxide. The whole was refluxed for about ten minutes. The dye separated from the chilled reaction. mixture. It was washed with ethyl alcohol, acetone and then water and finally recrystallized from methyl alcohol. It was obtained as reddish needles.

4,4-pyridocyanlne dyes can be prepared as illustrated below:

17.6 g. (3 mol.) of -picoline etho-p-toluenesulfonate, 8 g. (1 mol.) of 4-phenylmercaptopyridine ethiodide, 15 cc. of n-propyl alcohol and 4.2 g. (2.2 mol.) of triethylamine were refluxed for about 90 minutes. The dye was precipitated from the reaction mixture by adding diethyl ether. The precipitate was treated with 2.5 g. of sodium perchlorate dissolved in 3 cc. of Water. The dye, as the perchlorate, separated from the sodium perchlorate reaction mixture after carefully concentrating the reaction mixture. The dye was washed with diethyl ether and acetone to remove some colorless material and was finally twice recrystallized from a 5050 (volume 1) mixture of acetone and water. The perchlorate dye was obtained as beautiful brown-orange needles having a bright greenish-golden reflex and melt'-' ing at 196 to 198 C. with decomposition. Em-

ploying the method-p-toluenesulfonate instead of the etho, the l-ethyl-l' methyl dye is obtained.

The 4-phenylmercaptopyridine was prepared as follows:

15.5 g. (1 mol.) of 4-chloropyridine we e addwashed with ether and the free base generated with ammonia.

about 65 hours.

the ammonia reaction mixture with diethyl ether and purified by distillation. It boiled at 128 to 129 C. at 2 mm. of mercury pressure. It was converted into its ethiodide by heating one molecular proportion with one molecular proportion of ethyl iodide in a sealed tube at about 100 C. for about 17 hours. The solid obtained was washed with diethyl ether and recrystallized from acetone. .It melted at 178 to 180 C. with decomposition. The methiodide canbe formed more .readily by merely refluxing with methyl iodide for about 30 minutes. The methiodide melted at 174 to 176 C.

Selena-4'-cyanine dyes can \be' prepared as illustrated below:

2 g. (1 mol.) of l-me'thylbenzoselenazoleethicdide and 5.7 g. (2 mol.) of quinoline ethiodide were dispersed in 30 cc. of absolute ethyl alcohol containing 1.3 g. of potassium hydroxide. The whole was refluxed for about 10 minutes. The reaction mixture was cooled when the dye separated. The dye was filteredoff, washed with water, and then with acetone. It was recrystallized from methyl alcohol and obtained as red crystals.

. Aoenaphthothiazolo-Z-cyanine dyes can be prepared as illustrated below:

2-methyl-4,5(3,2)acenaphthothiazole (1.1 g., 1

mol.) and ethyl-p-toluenesulfonate (1 g., 1 mol.)

were heated in an oil bath at 130 to 140 C. for The brownish viscous mass of quaternary salt was dissolved in 20 cc. of absolute ethyl alcohol and 2-iodoquinoline ethiodide (2 g., 1 mol.) and triethylamine (1 g. 2 mol.) were added. The mixture was refluxed on a steam bath for about 30 minutes. The dye separated from cooled reaction mixture and was recrystallized from methyl alcohol. The purified dye was obtained as a dull red powder melting at 277 to 279 C. with decomposition 2-methyl-4,5(3,2)acenaphthothiazole from 3- aminoacenaphthene by acetylation thereof with acetic anhydride. 85 g. (1 mol.) of 3-aminoacenaphthene and 51.2 g. (1 mol.) of acetic anhydride in cc. glacial acetic acid'were heated on the steam bath for an hour. The acetylated productseparated from the chilled reaction mixture. The acetylated product, 10.5 g. (1 mol.) was suspended in 200 cc. of dry toluene and heated to to C. 5.6 g. (0.5 mol.) of phosphorous pentasulfide was added withstirring, and the mixture heated for 20 minutes longer. The toluene solution was decanted and the tarry residue was treated with an ice cold 25 cc. of 40% sodium hydroxide solution. The aqueous layer was treated with ice cold glacial acetic acid to precipitate the thioacetyl compound. The thioacetyl compound was dissolved in dilute sodium hydroxide and potassium ferricyanide solution added in excess. A light-brownish oil distilled.

The base was extracted from separated. The oil was taken up in ether, dried over anhydrous potassium carbonate, and finally 2-methyl-4,5 (3,2) acenaphthothi azole was obtained as a liquid boiling at 194 to 200 C. at 3 mm. of mercury and solidifying on cooling. It melted at 96 to. 97 C. Acenaphthothiazole-2'-cyanine dyes can be employed in practicing our invention.

Among the carbocyanine dyes which can be employed in practicing ourinvention are the fol-'- lowing:

The 2,2'-carbocyanine dyes-which can be represented by the following general' formula:

The thiacarbocyanine dyes which can be represented by the following general formula:

The dibenzothiacarbocyanine dyes which can be represented by the following general formula:

The oxaand dibenzoxacarbocyanine dyes which can be represented by the following general formula:

The selenacarbocyanine dyes which can be rep resented by the following general formula:

R R/ \X The oxathiacarbocyanine dyes which can be represented by the following general formula:

6 Y a I 5 a 7 s] 9 w L L 1C=CHC=CHC1 \i;

The oxabenzothiacarbocyanine dyes which can be represented by the following general formula:

The benzoxathiacarbocyanine dyes which can be represented by the following general formula:

, m thiabenaothiacarbocyanine dyes which can "a be represented by the following general formula:

I The thiaaolocarbocyanine' dyes whch can be represented by the following general formula:'

w J mi'iww bocysmn dyes which can be by the following general formula:

. ,4 v R/ x w Theoxa'selenacarbocyanine dyes which can be represented by the following general formula:

' In the above formulas of carbocyanine dyes,

70 A and B represent hydrogen, alkyl or aryl groups;

represents iodine) However, other dye-salts can be employed, such, for example, as the chlorides, bromides, perchlorates, alkylsulfates, or p-toluenesulfonates. We have further found it advantageous to employ carbocyanine dyes where-R 5 and R represent an alkyl group of from one to four carbon atoms, such as methyl, ethyl, isobutyl, normal propyl or p-hydroxyethyl, for example. The dyes wherein R. and R represent an alkyl group of two carbon atoms are particularly 10 useful in practicing our invention. The carbocyanine dyes can be substituted in their nuclei with simple substituents which do not interfere I with sensitizing properties, such, for example, as chloro, bromo, alkyl, alkcxy, amino or the like. As shown in the above formulas, dyes having a fused-on nucleus, for example, a benzene ring as in the case of dlbenzothiacarbocyanine dyes, can be employed.

The above formulas of representative types of go carbocyanine dyes are not intended to limit our inventiom'as there are still other well known carbocyanine dyes not depicted above. However, the foregoing. will serve to instruct those skilled in the art as to which of the simple cyanine dyes can advantageously be employed in practicing our invention.

The methods of preparing the different carbo- -cyanine dyes are well known and described in various patents and printed publications. Howan ever, the following will aid those skilled in the art in quickly locating the available information.

2,2'-carbocyanine, oxacarbocyanine and thiacarbocyanine dyes can be prepared as described by Hamer in J. Chem. 800., page 2796 et seq.-

.(192'7) Selenacarbocyanine dyes can be prepared as described by Clark in J. Chem. Soc., page 2313 et seq. (1928). Dibenzothiacarbocyanine dyes can be prepared as described in U. S. Patent 1,969,444. Dibenzoxacarbocyanine dyes can be 40 prepared as described in U. S. Patent 1,939,201. 5,6,5',6'-dibenzo-2,2-carbocyanine dyes can be prepared as described by Mees and Gutekunst in Ind. Eng. Chem., vol. 14, page 1060 et seq. (1922). T'hiazolocarbocyanine dyes can be prepared as described by Fisher and Hamer in J. Chem. 800.,

page 2502 et seq. (1930). Thiacarbocyanine dyes containing a substituent at the central carbon atom of the trimethenyl chain can be prepared as described in U. S. Patents, 1,934,657; 1,934,658; and 1,934,659. Dibenzothiacarbocyanine dye containing a substituent at the central carbon atom of the izrimetherlyl chain can be prepared as described in U. 5. Patent 1,969,444.

Selenacarbocyanine dyes containing a substit- The p-acetanilidovinyl derivatives are advan- 7o tageously employed. The method is known in the art and the following examples are illustrative:

To prepare oxa-, thia-, and selena-2'-carbocyanine dyes which can be employed in practicflu'xing' temperature for about 20 minutes.

by the following eneral formula:

1C=CH-C H=CH-C 4) 2 wherein Y represents oxygen; sulfur or selenium,

R and R represent alkyl groups and- X represents an acid radical, a p-anilinovinyl derivative of quinoline is first prepared by fusing an intimate mixture one molecular proportion of duinaldine ethiodide with one molecular proportion of diphenyl-iormamidine' at'150 C. to about 180 C. for about 10 minutes with stirring. The cooled reaction mixture was ground with acetone, filtered, and recrystallized from methyl alcohol. One ,part of the fl-anilinovinyl derivative and one part of the ethiodide of l-methylbenzoxazole, l-methylbenzothiazole or l-methylbenzoselenozole are dispersed in about two-parts of pyridine and the wholelis refluxed for from about 10 to about minutes. The dye separates from the chilled reaction mixture. Precipitation of the dye is facilitated by addition of diethyl ether. The dyes can be washed with acetone and recrystallized from methyl alcohol.

Oxathiacarbocyanines can be prepared by first reacting l-methylbenzoxazole ethiodide with diphenylformamidine in acetic anhydride at a re- The p-a'cetanilido compound separates upon cooling and is washed with acetone. One part of thep-acetanilidovinyl compound and one part of l-met hylbenzothiazole 'ethiodide are refluxed in pyridine solution for about 20 minutes. The

dye separates from the chilled reaction mixture.

Diethyl ether facilitates separation. The dye can be recrystallized from methyl alcohol. To prepare oxabenzothiacarboeyanine 'dyes the 1- methylbenzothiazole ethiodide is replaced by 1- methyl-a-naphthothiazole or 2-methyl-pnaphthothiazole ethicdides. Insteadof forming the dyes in pyridine, the p-snilinovinyl compounds can be reacted with cyclammonium quaternary salts in acetic anhydride containing sodium acetate to bind' the elements of acid eliminated during dye formation. g

Among the organic amino compounds which can be employed in practicing our invention-are I the following:

The aminoquinolines, for example:

- N(CH:)\:,

I v 2,177,036 ing our invention and which can'berepresented k fi-amlnol-phehylbenzothiazole S-smino-l-mercaptobenmthiarol S /1 H05 c g zc-NH;

2-amino-4-phenylthiszole Still other amino heterocyclic nitrogen bases are: 2-amino-4-methylbenzothiazole, 4-amino-1- methyl-p-naphthothiazole, iaminothiazole, 8- aminoquinoline, z-aminopyridine, l-aminobenzoxazole, and -amino-p-naphthothiazole for example. The heterocyclic nitrogen base can have more than one amino group substituent. The

amino group is advantageously on the nucleus, as in fi-dimethylaminoquinoline, or 4-dimethylamino-l-methylbenzothiazole for example. Het- "erocyclic 'nitrcgen bases containing dialkylamino groups, particularly dimethy'l-amino, are especially useful. The position of the amino group substituent-appears to alterthe supersensitizing properties of'-'the amino heterocyclic nitrogen bases. In the benzazole bases, 1. e. benzathiazole and benzoxazole for example, an amino group, particularly a dimethylamino group, in the 6- position gives rise to strongly supersensitizing aminoheterocyclic nitrogen bases. We have Kohlenstoif-Verbendungeh and Meyer-Jacobsons Lehrbuch der or anischen Chemie.

The objects of our invention can be accomplished by incorporating one or more sensitizing simple cyanine or carbocyanine dyes, together with one or more organic amino compounds in a photographic emulsion. Our invention is particularly directed to the ordinarily employed gelatino-silver-halide emulsions. However, our supersensitizing combinations can be employed in emulsions in which the carrier is other than gelatin, for example, a resinous substance'oi cellulosic derivative which has substantially no deleterious effect on the light-sensitive materials. As silver halide emulsions, we include such emulsions as are commonly employed in the art, but more particularly the customarily employed silver chloride and. silver bromide emulsions. The silver chloride and silver bromideemulsions may contain other salts which may be light sensitive. By way of illustration, the herein described supersensitized' emulsions were prepared employing an ordinary gclatino-siiver-bromide emulsion oi ordinary concentration iap= proximately 40 g. of silverhalid'e per liter). The

dyes were generally employed in concentrations of from 10 to 20 mg. of the per but can be employed in cflncnttatihht'sdveral times greater or less than that. Hie tizing substance, l. e. the organic-amino bdrm pound was generally employed iniconce'ntrationa of about 20 mg. per liter of be employed in concentrations several example. The most favorable conditions (or or less than that. The ratio-o; .i.. dyeto the concentration of substance can vary widely'irom l0:1rto 1:100, for

emulsions separately or together with the sensitizing substances. It is convenient to'iirat add the dyes in the form or solutions in appropriate solvents. Then 'the supersensitinne substance can be added, advantageouslyl'jn the term of' a solution. The solvents employed mustgot course, be compatible with theem'ulsions, substantially free from any deleterious eitect on the light-sensitive materials. capable of. d8- solving the dye or supersensitlzingsuhstances.

Methanol has provensatisiactory as'a solvent for both the dyes and the awareness in practicing our invention, be employed. The edyes and supersensitizing substances can advantageously be incorporated in the finished, washed emulsion and should be uniformly distributed throughout the .emulsion.

The following procedure is satisfactory: A stock solution of the dye or supersensitizing substance is prepared by dissolving the dye or Impersonaltizing substance in a suitable solvent, such as methyl or ethyl alcohol or acetone; Then; to

liter of a fiowable 'g'elatino-"silver halide sion, an amount of the so-prepared solution, diluted somewhat with water, it? desired. containing the desired amount ofdye unsupersensitlzing substance is slowly added with stirring. Stirring is continucduntiithe dye or supersensitizing subotanceis thoroughly} incorporated. The supersensitized emulsion; can theii be coated out upon a suitable support, such; as glass, cellulose derivative, resinous P p r or the like, to a suitable ailcwed to dry. The detail: 0!

methods are well known to those in "the The .amountoi dye'or supersensitizing sung" stance actually incorporated will, 0 course, vary from dye to dye and supersensiti to supersensitiz ng substance, according to the" emulsion employed and according tothe su'persensitizing 'eiiect desired. The regulation and adoption ofthe most economical and useful portions will be apparent, those skilled in the emulsion art upon making the ordindry observe tions and tests customarily employed in the art.

Accordingly, the foregoing procedures and proportions are'to be regarded only illustrative.

ethylthia 2' cyanine carbocyanine methylbenzothiazole', 2-amlno 4 methylbem thialoletions which can advantageously be employed in.

practicing our invention. These illustrations are not intended to be limiting. 1 A; 6 dimethylamino l methylbenmthiazole with one or more of the following dyes:

l,l'-cllethyl-2,2'-cyan ine iodide, 2-methyl-1'- ethylthia 2 cyanine iodide, 2,1 diethyl 4 chl'o'rthia-2' cyanine iodide, 2,1'-'diethyl-3,4- benzthia 2' cyanine iodide, 2,1 diethyl. 6'- methyl-3,4-benzthia-2'-cyanine iodide, 8,1'-diethyl-4-phenyloxazolo-2 -cyanine iodide, 219

ethylthia-Z-ca.rbocyanine iodide, 2,2'-dimethyl- B-ethylthiacarbocyanlne iodide, 2,2"-.diethyl-8- methyl 3,4,3',4 dibenzthiacarbocyanine chloride, 2,2,8-triethyl-4,4'-dichlorothiacarbccyanine iodide, 2,2',8-triethylselenacarbocyanine. iodide, 2,2-'-diethyl-8-methyl-3',4'-benzoxathiacarbocyanine iodide, 1,1-diethyl-2,2'-carbocyanine chloride, 2,2 diethyloxacarbocyanine iodide.

B. G-dimethylaminoquinaldihe with one or more of the following dyes:

1,1-diethyl-2,2'-cyahine iodide, 2-methyi-l'- iodide, 2,1 -d ie'thyl.-4- chlorothia 2'-cyanine iodide, 2,1'-di ethyl -3,4-

- benzthia 2' cyanine iodide, 2,1 methyl-6'- methyI-3,4-benzthia-2-cyanine iodide, 2,'l"- dlethylthia-2-carbocyanine iodide, 2,2 -diethyi- 3,4,3!-dibenzothiacarbocyanine iodide, 2,2-'diethyl-B-methylthiacarbocyanine iodide, 2,2'-di- .methyl-13-ethy1thiacarbocyanine iodide, flfl' di ethyl -8- methyl-3,4,3,4-dibenzthiacarbocyahhie chloride, 2,2,B-triethylAA'-dichlorothiacarbccyanide iodide, 2,2 dlethyl 8 methyl 324'- benzoxathiacarbocyanine iodide, l,1'-dlethyl-2,2"-'

chloride, 2,2 diethyloxacarbocyanine iodide, 2,2 diethylthiacarbocyanlne iodide. l C. 6-dimethyiaminolepidine with one or of. the following dyes:

*l,l'-diethyl-2,2'-cyanine iodide, 2,2-,8-'triethyl- 4,4-ch"orothiacaibocyanine iodide, il,2'-dimetlwlt-ethylthiacarbocyanine iodide.

D. l -amlnobenzothiazole with one or'more oi the following dyes: A

1,1'-diethyl-2,2'cyanlne iodide, 2,2' ,8-trlethyl 4,4' dichlorothiacarbocyanine iodide, ,2,2'-d1-: methyl-8-ethylthiacarbocyanine iodide.

B. One or more of the following amino hetero cyclic nitrogen bases- I S-aminmI-methylbenzothiazole, 5-acetamtno- 1- *methylbenjzothiazole, 4 dimethylamino 1.-

more

thiazole, 1 anilinobenz'othiazole, 5 if phenylbenzothiazole, 5-amino-l-mercaptobenzo with one or more of the following dyes: '1,1'-diethyl-2.2-cyanine iodide, 2,2,8-triethyl- 4,4 dichlorothiacarbocyanine iodide, tW-dis methyl-B-ethylthiacarbocyanine iodide.

The accompanying drawing is by we! 011ilustration and depicts the supersensitizhig eflect in four of our new, comblnations. Each figure of f,

the drawing is a diagrammatic reproduction or two spectrograms showing first, the sensitivity 0! a silver bromide emulsion containing a simple cyauihe or carbocyarilne dye (represented by the dotted line in each figure) and showing second, 1'

the sensitivity 01' thesame silver bromide emulsion containing a mixture or combination. of the said simple cyanine or carbocyanine dye with an organic amino compound (represented by the solid line in each figure). The supersensitizing eflfect is apparent from theflgures.

In Fig. 1, curve Arepresents the sensitivity of an ordinary gelatino-silver-bromide emulsion containing 1,1-diethyl-2,2'-cyanine iodide in a concentration of about15 mg. per liter of emulsi n. Curve B represents the sensitivity of the sa e emulsion containing 1,1'-diethyl-2,2'- cyanine iodide in a concentration of aboutv 15 mg. per liter of emulsion and containing-B-dimethylamino-bmethylbenzothiazole in a concentration of about 10 mg. per liter of emulsion. The increase in green sensitivity is about 400%.

In Fig. 2, curve C represents the sensitivity oi an ordinary gelatino-silver-bromide emulsion containing 2 methyl 1' .ethylthia-2'-cyanine iodide in a concentration of about 15 mg. per liter of'emulsion. Curvel) represents the sensitivity oi the same emulsion containing 2-methyll'-ethylthia-2'-cyanine iodide in a concen on 01' about 15 per liter and containing dimethylaminoquinaldine. in a concentration of about 40 mg. per liter of emulsion. The increase in green sensitivity is about 280%.

In Fig. 3, curve E represents the sensitivity of an ordinary gelatino-silver-bromide emulsion containing l,l'-diethyl-2,2'-carbocyanine iodide in a concentration or about 10 mg. per liter of emulsion. Curve F represents the sensitivity oi the same emulsion containing 1,1'-diethyl-2;2'-. carbocyanine iodide in a concentrationoi about 10mg. per liter oi emulsion and containing B-dimethylaminoquinaldine in a concentration of about 40 mg. per liter of emulsion. The increase in red sensitivity is about 100%.

In Fig. 4, curve G represents the sensitivity at an ordinary gelatino-silver-bromide emulsion containing -2,2'-diethyl 8 methyl-3,4,8',4'-dibenzothiacarbocyanine iodide in a concentration of about 10 mg. per liter of emulsion. Curve H represents the sensitivity of the same emulsion containing 2,2'-di ethyl 8 methyl-3,4,3',4'-di- 'b'enzothiacarbocyanine iodide in a concentration of about 10 mg. per liter of emulsion and containing G-dimethylaininoquinaldine in a concentration of 40 mg. per liter of emulsion. The increase in red sensitivity is about 100%.

The spectrograms corresponding to the flgures oi the accompanying drawing were made in a wedge spectrograph. Each horizontal line represents'an incident-light intensity of about onetenth of that of the line below it. The spectrograms with and without the supersensitizing substance were made from plates coated irom the same batch of emulsion, dried and processed together. a

Still further illustrations depicting diagrammatically the supersensitizing eii'ects attainable by practicing our invention could be given, but. the foregoing will suflice to teach those skilled in the art the manner of practicing our invention and the principles of sensitizing photographic emulsions withour supersensitizing combinations.

We understand the term amino group to include unsubstituted amino groups as well as substituted amino groups, such as monoalkylamino, dialkylamino or acylated amino groups.

What we claim as our invention and desire to be secured by Letters Patent of the United States 1. A photographic silver halide emulsion 'conalmost taining a superscnsitising combination oiat'lcast one non-sensitizing heterocyclic nitrogen base containing an'aminc of which amino group group,- he nitrogen atom is not one or the nuclear atoms in the heterocyclic ring the heterocyclic nitrogen base. together with at least one sensi tizing cyanine dye selected from the group con sisting oi.2'-cyanine dyes, 4'-cyan1ne dyes, 2'- pyridocyanine dyes, Q-pyridoeyanlne dya and ,a'-carbocyanine dyes.

2. A photographic geiatino-silver-halide emulsion containing a supersensitizing combination of at least one non-sensitizing heterocyclic nitrogen base containing an amino group, the nitrogen atom of which amino group is not one of the nuclear atoms in the heterocyclic ring of the heterocyclic nitrogen base, togetherylth at least one sensitizing cyanine dye selected from the group consisting of 2'-cyanine dyes, ef-cyanins dyes, 2'-pyridocyanine dyes, 4'-pyridocyanins' dyes and a,a'-carbocyanine dyes.

3. A photographic gelatino-silver-halide emulsion containing a super-sensitizing combination of at least one sensitizing heterocyclic nitrogen base containing an amino group, the nitrogen atom of which amino group is not one of the nuclear atoms in the heterocyclic ring of the heterocyclic nitrogen base, together with at least one sensitising simple cyanine dye selected from the group consisting of 2'-cyanine dyes, 4'-c'yanine dyes,

2'-pyridocyanine dyes and 4'-pyridocyanine dyes.

4. A photographic gelatino-silver-halide emulsion containing a supersensitizing combination 0! at least one non-sensitizing heterocyclic nitrogen base containing an amino group, the nitrogen atom oi which amino group is not one 01' the nuclear atoms in the heterocyclic ring of the heterocyclic nitrogen base, together with at least one sensitizing aM-carbocyanine dye.

5. A photographic gelatino-silver-halide emulsion containing a supersensitizing combination of at least one non-sensitizing heterocyclic nitrogen base containing an amino group, the nitrogen atom 01' which amino group is not one of the nuclear atoms in the heterocyclic ring of the heterocyclic nitrogen base, together with at least one sensitizing pseudo-cyanine dye.

6. A photographic gelatino-silver-halide emulsion containing a supersensitizing combination of at least one non-sensitizing heterocyclic nitrosen base containing an amino group, the nitrogen atom of which amino group is not one of the nuclear atoms in the heterocyclic ring of the heterocyclic nitrogen base, together with-at least iane sensitizing thiacarbocyanine dye.

7. A photographic gelatino-silver-halide emulsion containing a supersensitizing combination of at least one non-sensitizing heterocyclic nitro-' gen base containing an amino group, the nitrogen atom oi which amino group is not one of the nuclear atoms in the heterocyclic ring of the heterocyclic nitrogen base, together with at least one sensitizing 2,2'-cyanine dye- 8. A photographic gelatino-silverhalide emulsion containing a supersensitizing combination of at least one non-sensitizing heterocyclic nitrogen base containing an amino group, the nitrogen atom of which amino group is not one of the nuclear atoms in the heterocyclic ring of the heterocyclic nitrogen base, together with at l ast one sensitizing dibenzothiacarbocyanine dye.

9. A photographic gelatino-silver-halide emulsion containing a supersensitizing combination of at least one non-sensitizing azole base containing an amino group. together with at least-one I v 2,177,685 sensitizing cyanine dye selected from the group consisting of z' -cyanine dyes, 4'-cyanine dyes, 2'- pyridocyanine dyes, 4-pyridocyanine dyes and ,'-carbocyanine dyes.

10. A photographic gelatino-silver-halide emulsion containing a supersensitizing combination of at least one non-sensitizing thiazole base containing an amino group, together with at least ','-carbocyanine dyes. 12. A photographic gelatino-silver-halide emulsion containing a supersensitizing combination of at least one benzothiazole base containing a dialkylamino group together with at least one sensitizing thiacarbocyanine dye. I

18. A photographic geiatino-silver-halide emulsion containing a supersensitizing combination of at least one benzothiazole base containing a dimethyiamino group in that-position together with at least-one sensitizing 2,2f-dialkyi-8-alblthiacarbocyanine dye.

14. A photographic gelatino-silver-halide emulsion containing a supersensitizing combination of at. least one non-sensitizing heterocyclic nitrogen base containing a dialkylamino group togather with at least one sensitizing 2,2'-eyanino 15. Aphotographic gelatino-silver-halide emulsion containing a supersensitizing combination of B-dimethylaminoquinaldine together with at least one sensitizing 1,1'-diethyl-2,2'-cyanine dye.

16. A photographic gelatino-silver-halide emulsion containing a supersensitizing combination of .at least one non-sensitizing quinoline base containing an amino group, together with at least one sensitizing cyanine dye selected from the group consisting of 2-cyanine dyes, 4'-cyanine dyes, 2'-pyridocyanine dyes, 4'-pyridocyanine dyes and a,-carbocyanine dyes.

17. A photographic gelatino-silver-halide emulsion containing a supersensitizing combination of at least one non-sensitizing G-dialkylaminoquinoline base, together with at least one sensitizing cyanine dye selected from the group consisting of 2-cyanine dyes, 4'-cyanine dyes, 2'-pyridocyanine dyes, 4'-pyridocyanine dyes and e carbocyanine dyes.

18. A photographic gelatino-silver-halide emulsion, containing a supersensitizing combination of at least one non-sensitizing quinoline base containinga dialkylamino group together with at least one sensitizing dibenz'othiacarbocyanine dye.

19. Aphotographic gelatino-silver-halide emulsion containing a supersensitizing combination of G-dimethylaminoquinaldine together with at least one sensitizing 2,2'- -dialkyl-8-alkyl-3,4,3',4'- dibenzothiacarbocyanine dye.

BURT H. CARROLL. EDWARD P. DAVEY. 

